Reduction of energy consumption in radio devices is always desired, and particularly for radio devices that rely on battery. Most energy is consumed when transmitting, and a power amplifier, having its task to provide the radio power to antenna, will of course consume some amount of energy. However, not all energy provided as supply power to the power amplifier becomes signal power for the radio signal. Thus, the power amplifier and the transmitter have a degree of power efficiency, i.e. signal power in relation to supply power. It is therefore a desire to provide a radio, and a way to operate it, which provide good efficiency.